const obj = {
	name: 'cat',
	age: 19,
	gender: 'female'
}
Object.prototype.like = 'running'



Object.prototype.my_keys = function() {
	let res = []
	for (let key in obj) {
		obj.hasOwnProperty(key) && res.push(key)
	}
	return res
}
const keys = Object.my_keys(obj)
console.log(keys);
